Laser machining

ABSTRACT

The invention relates to an adapter for coupling a laser treatment device to an object for treatment, whereby the adapter has an input side, which may be fixed relative to the laser treatment device, by a locking mechanism and which may be fixed to the object, for alignment of the object relative to the laser treatment device. A scanned laser beam is introduced on the input side, from the laser treatment device, along a beam path to the object with a reference structure. The reference structure lies on the beam path of the adapter and may be optically detected by means of the laser beam scanned over the region.

The invention relates to an adapter for coupling a laser processingdevice with an object to be processed, said adapter comprising an inputside, which can be fixated relative to the laser processing device via alocking mechanism, being attachable to the object for positioning of theobject relative to the laser processing device, transmitting a laserbeam to the object along a beam path, said laser beam having beensupplied to the input side by the laser processing device and scannedover a certain region, and comprising a reference structure, inparticular relating to the orientation of the adapter. The inventionfurther relates to a laser processing device for such adapter, saiddevice comprising a beam deflecting unit for scanning a laser beam.

In material processing by means of laser radiation, laser beam scanningof the zones to be processed on the object is generally employed. Theprecision of positioning the laser beam usually determines the precisionachieved in said processing. Focussing of the laser beam into aprocessing volume requires exact three-dimensional positioning.Therefore, for high-precision processing it is usually indispensable tohold the object in an exactly defined position relative to the laserprocessing device. The above-mentioned adapter is intended for suchapplications because it fixates the object to be processed or imparts adesired shape to the deformable surface of the object to be processed.

This is required, in particular, for micro-processing of materials whichhave only a low linear optical absorption in the spectral range of theprocessing laser radiation. For such materials, usually non-linearinteractions between the laser radiation and the material are employed,in most cases in the form of an optical breakthrough generated in thefocus of the laser beam. Since the processing action takes place only inthe laser beam focus, exact three-dimensional positioning of the focalpoint is indispensable. Thus, an exact depth position of the focusposition is required in addition to a two-dimensional deflection of thelaser beam. The above-mentioned adapter facilitates this because itensures constant optical conditions, which are also known with a certainprecision, in the beam path to the object, or because known opticalconditions, in particular refractive conditions, are present in the beampath when the adapter contacts the object.

A typical application for such an adapter is the ophthalmic surgeryprocedure known as LASIK, wherein a laser beam is focussed into thecornea on a focal point which is of the order of magnitude of onemicrometer. A plasma then forms in the focus, which plasma causes localseparation of the corneal tissue. By suitable serial arrangement of thelocal separation zones generated in this manner, macroscopic cuts arerealized and a certain partial volume of the cornea is isolated. Adesired change in refraction is then achieved by removal of said partialvolume, so that correction of a visual defect is possible.

Exact positioning of the laser beam is indispensable to carry out themethod. For this purpose, a contact lens provided with reference marksis known from U.S. Pat. No. 6,373,571, said lens realizing an adapter ofthe aforementioned type. This contact lens is adjusted by means of aseparate measurement device, which results in a relatively complexstructure. The aforementioned adapter serves two functions: not onlydoes it ensure the required optical properties for the laser beam toenter the cornea, but it also fixates the eye, preferably with respectto several degrees of freedom, particularly preferably with respect toall possible degrees of freedom. This prevents movements of the eyerelative to the laser processing device.

An example of such adapter is described, for example, in WO 03/002008A1. The adapter referred to therein as “applanation lens” comprises asuction ring, which is attached to the eye by means of suction. Insertedin the suction ring is a glass plate, which is pressed into the suctionring by means of a bracket. The bracket simultaneously also fixes aflange part to the suction ring, which flange part is permanentlyattached to the laser processing device. The multi-component adapter ofWO 03/002008 A1 presses the surface of the cornea flat, thus achievingsimple standard geometries. However, this is very inconvenient for thepatient. Moreover, applanation of the corneal surface is undesired insome surgical operations. A further example of an adapter of theaforementioned type is described in EP 1,159,986 A2. It has reticlemarkings at the edge of a holder, which make visual alignment possiblefor the surgeon. However, the precision achieved thereby is not alwayssufficient. Therefore, it is an object of the invention to improve anadapter or a laser processing device of the aforementioned type suchthat high-precision laser processing is easily possible.

This object is achieved by an adapter for coupling a laser processingdevice with an object to be processed, said adapter comprising an inputside which can be fixated relative to the laser processing device via alocking mechanism, being attachable to the object for orientation of theobject relative to the laser processing device, transmitting a laserbeam to the object along a beam path, said laser beam having beensupplied to the input side by the laser processing device and scannedover a certain region, and comprising a reference structure, whichreference structure is located in the beam path of the adapter and isoptically detectable by means of the laser radiation scanned across saidregion. The reference structure for alignment of the adapter ispreferably detectable with respect to its position.

The object is further achieved by a laser processing device for the useof such an adapter, said device comprising a beam deflecting unit forscanning a laser beam, a detecting unit for optical detection of thereference structure by means of the laser beam, and a control unitreading out the detecting unit, which control unit controls the beamdeflecting unit, determines the actual position of the adapter on thebasis of the optically detected reference structure and considers saidposition when controlling the beam deflecting unit.

The reference structure provided in the beam path of the adapter allowsthe laser processing device to exactly detect the position of theadapter and thus of the object.

However, the function of the adapter according to the invention is notlimited to producing an exact alignment or a very precisely knownalignment. The laser processing device which can be sensed by the laserbeam also allows the function of the laser processing device to bechecked in the simplest manner with respect to laser beam deflection.For this purpose, a laser beam is guided over the reference structureduring operation of the laser processing device for control purposes;detection of the reference structure is assigned to the correspondingcontrol value of the laser beam deflection, and any deviation betweenthe control value and the actual laser beam deflection is determinedfrom the known position and the assigned control value of the laser beamdeflection. This difference can be considered for correction of thedeflection control of the laser beam during subsequent operation.Optionally or additionally, if the need for correction exceeds athreshold value, operation of the laser processing device may beblocked.

The laser radiation used in doing so may be identical with theprocessing laser radiation; however, this need not be the case.Advantageously, the laser processing device will employ the same beamdeflection means, e.g. a scanning unit, for scanning the laser radiationwhich are also used for the processing laser radiation, because onlythen is the aforementioned checking of the beam deflection possible.Thus, the region in which the reference structure is located is thepotential processing zone.

If, on the other hand, an independent laser and beam deflecting unit isused for positional detection of the adapter by means of detection ofthe reference structure, an optically simpler structure may be achievedin some cases.

For the reference structure, any design of the adapter is suitableallowing detection of the position of the adapter. Conveniently, spatialzones will be designed which differ from the remaining beam path of theadapter in at least one optical property. Said optical property may be,for example, the reflection property or, more generally, the index ofrefraction of said spatial zone. The reference structure may thencomprise, for example, control points or control lines, wherein backreflection, scatter or absorption or dispersion, respectively, of theradiation may characterize a spatial zone.

To distinguish the reference structure, a spectral range is aparticularly suitable optical property which is above the UV absorptionbands of optical materials, i.e. above 400 nm. A possible upper limitresults from the desired spatial resolution and may typically be 2 μm.For the optical property, a spectral range of between 0.8 μm and 1.1 μmis preferably used. Depending on the spatial resolution, the markingstructures may have dimensions of between 1 μm and 100 μm, preferablybetween 3 μm and 10 μm.

In principle, a great variety of mechanisms in the adapter are suitableto transmit to the output side the radiation supplied to the input side.For ophthalmic procedures, the adapter will be conveniently designed inthe manner of a contact glass, so that the beam path comprises, at leastin part, a material, in particular glass, which is transparent forprocessing laser radiation. In a particularly convenient embodiment, theadapter comprises a cylindrical or frustoconical body one end surface ofwhich is provided as the input side.

In addition, the adapter may have an output side which imparts a desiredshape to a deformable surface of the object, e. g. by attaching theadapter to said deformable surface.

As already mentioned, the reference structure may allow to detect theactual spatial position of the adapter. Since the adapter is at the sametime securely attached to the object, the actual position of the adapteralso provides information on the position of the object relative to thelaser processing device. Therefore, it is preferred for the referencestructure to reflect the actual spatial position of the adapter. Thus,optical detection of the reference structure allows to obtaininformation on the orientation of the object relative to the laserprocessing device, so that the optical conditions for coupling-in of thelaser beam on the object are known and high-precision laser processingis possible.

The laser processing device for the adapter according to the inventionis capable of optically detecting the reference structure by means ofthe detecting unit and to consider in the control unit the thereby knownactual position of the adapter for control of the beam deflecting unit.If the laser processing device is provided for the LASIK method, thecontrol unit can consider the identified actual position for controlsuch that the breakthroughs to be generated are located at the desiredlocations.

In this case, the treatment laser will usually operate in a pulsedmanner. Therefore, in this respect an embodiment using a pulsedtreatment laser is preferred for an ophthalmic procedure, wherein theobject is the cornea and the control unit controls the beam deflectingunit and the treatment laser such that the laser beam generates opticalbreakthroughs at predetermined locations in the eye and, in doing so,respectively considers the identified actual position of the adapter orthe desired shape of the cornea identified by said information.

As already mentioned, the reference structure of the adapter may serveto validate the function of the beam deflecting unit, e.g. of a scanningunit or of a zoom unit, during operation. It is therefore convenientthat the laser processing device intermittently direct a laser beam,which may preferably also be the treatment laser beam, onto thereference structure by means of the beam deflecting unit deflecting thetreatment laser beam, in order to check the operation of the beamdeflecting unit. Any difference between the control of the beamdeflecting unit and the known actual position of the reference structuremay then be recognized in the further operation of the laser processingdevice. If such difference exceeds a certain limit value, the processingoperation may be blocked.

Thus, a method is provided wherein the detection of borders betweenregions having different indices of refraction is effected, the positionof said regions in the adapter being known and said regions beinglocated in this component which is at least temporarily fixed to thelaser processing device. Of course, the adapter may also be permanentlyattached, and not just temporarily. With a permanently attached adapter,the detection of the reference structure for checking the actualposition of the adapter can also be carried out for maintenance purposesonly during inspection work. The method comprises the steps of:

-   -   1. Mounting the adapter to the laser processing device.    -   2. Searching at least one reflector zone 25, wherein searching        is understood to be automatic position determination within a        spatial search area that is given by the expected location of        the reflector zone 25. Position determination is effected in        that (confocal) detection of the reflector zone 25 is carried        out on the basis of the reflected or scattered signal of a laser        beam, preferably of the treatment beam 4, whose focus 13 is        three-dimensionally moved through the search area in a suitable        manner by spatial shifting by means of the scanning unit 6 and        the projection optics 9.    -   3. Storing the position thus determined, preferably for all        three spatial directions. Steps 2 and 3 may be performed for        some or all of the reflector zones.    -   4. Calculating the deviation as the difference between the        measured location of the reflector zone and the expected        position.    -   5. Checking the deviation for permitted values and considering        the deviation in the beam deflection control, if possible.

It is a further object of the invention to improve an adapter or a laserprocessing device, respectively, of the aforementioned type such that itis not stringently required to work with a plane geometry.

In a further embodiment of the invention, this object is achieved by anadapter for coupling a laser processing device with an object to beprocessed, said object having a deformable surface, wherein the adaptercomprises an input side which can be fixated relative to the laserprocessing device via a locking mechanism, has an output side which canbe made to contact the deformable surface and to thereby impart adesired shape to it, with the adapter being attachable to the object,transmitting a laser beam along a beam path to the surface contactingthe output side, said laser beam having been supplied, scanned over acertain region, to the input side by the laser processing device,wherein the adapter comprises marking structures in the beam path, whichare optically detectable by means of the laser radiation scanned oversaid region and which encode information characterizing the adapter.

The object is further achieved by a laser processing device for such anadapter, said device comprising a beam deflecting unit for scanning alaser beam, a detecting unit for optical detection of the markingstructures by means of the laser beam and a control unit reading out thedetecting unit, said control unit controlling the beam deflecting unit,determining the information which characterizes the adapter andconsidering said information when controlling the beam deflecting unit.Thus, the reference structure previously used for adjustment of or fordetermining the position of the adapter, respectively, is now providedas marking structure serving to encode information. Of course, acombination is also possible.

The adapter usually serves to establish secure input-side coupling withthe laser processing device. The adapter's input side which faces thelaser processing device is therefore provided with suitable means for asecure connection to the output (e.g. distal end) of the laserprocessing device or its optical system, respectively, which output isdirected toward the object, so that secure fixation with respect to thelaser processing device is possible by means of a locking mechanism. Forthe locking mechanism it is conceivable, for example, to provide aflange surface on the adapter.

On its output side, the adapter ensures that the deformable surface ofthe object has a desired shape. Suitable means are provided for mountingthe adapter to the object; in an ophthalmic application, a suctionmounting means, e.g. a suction ring as known from WO 03/002008 A1 orfrom EP 1,159,986 A2, may be employed.

The marking structures provided in the beam path of the adapter allowthe laser processing device to obtain information on the adapter used.Said information may be, for example, a model no. of the adapter, anindividual designation or information on the desired shape which theadapter imparts to the deformable surface.

In order to provide said information directly to the laser processingdevice, the marking structures are arranged in the beam path such thatthey are optically detectable by means of the scanned laser radiation.Separate information transmission mechanisms may be obviated thereby;instead, the laser processing device may detect the marking structuresby means of suitable laser beam sensing and, thus, extract theinformation characterizing the adapter.

The adapter as well as the laser processing device according to theinvention enable the use of application-adjusted adapters withoutrunning the risk of erroneously working with operational parameters thatdo not suit the currently used adapter. This eliminates a possiblesource of error and increases the overall laser processing quality.

Conveniently, one will strive to use as few laser radiation sources aspossible in the laser processing device, because any additional laserradiation sources will usually be connected with further costs. Thus, itis conceivable to use the laser beam emitted by the treatment laser alsofor optically detecting the reference structure. To do so, however, thepeak intensity and the average power have to be reduced, on the onehand, in order to avoid stress on the object to be processed, i.e. thepatient's eye, and to prevent, above all, a processing effect on theadapter. Therefore, it is convenient to provide a means for reducing theenergy of the laser beam, said means at least temporarily reducing theenergy of the laser beam emitted by the treatment laser for opticaldetection of the reference structure. For this purpose, e.g. an energyreducer may be coupled into or activated in the beam path.Alternatively, use can also be made of the property of conventionalpulsed lasers, which consists in emitting background radiation ofstrongly reduced power between the individual laser pulses. Saidbackground radiation can be used for detection of the referencestructure, and an energy reducer can then be omitted.

At which position in the beam path the reference structure is located isnot decisive for the adapter according to the invention; what isessential is merely that it should be possible to sense the referencestructure by means of scanned laser radiation emitted by the laserprocessing device; thus, it is located within a space region in whichthe laser processing device can position the focus of the laser beam.

The laser radiation used in doing so may be identical with theprocessing laser radiation; however, this need not be the case.Conveniently, however, for scanning of the laser radiation the laserprocessing device will employ the same scanning unit which is also usedfor the treatment laser radiation. Thus, the region in which thereference structure is then located is the potential processing zone.

As marking structure, any design of the adapter is suitable which allowsinformation to be retrievably stored within the beam path. The alreadymentioned design of spatial zones is particularly suitable. The markingstructures may then be designed, for example, in a similar manner as abar code, wherein back reflection, scatter or absorption or dispersion,respectively, of the radiation may characterize a spatial zone.

To distinguish the reference structure, a spectral range is aparticularly suitable optical property which is above the UV absorptionbands of optical materials, i.e. above 400 nm. A possible upper limitresults from the desired spatial resolution and may typically be set at2 μm. For the optical property, a spectral range of between 0.8 μm and1.1 μm is preferably used. Depending on the spatial resolution, thereference structure may have dimensions of between 1 μm and 100 μm,preferably between 3 μm and 10 μm.

The information encoded by the marking structures may characterizewhatever features of the adapter, e.g. geometric or material properties.A particularly preferred application is to be seen in describing thedesired shape that is defined by the output side of the adapter, or instoring information about it. For example, the marking structures canrepresent the refractive properties of the desired shape.

As already mentioned, a convenient application for the adapter is thedesign as a contact glass for ophthalmic surgery. Of course, it may alsobe a special accessory which replaces the actual contact glass or isattached to the actual contact glass for the purpose of a measurementprior to treatment.

In one variant, the laser processing device according to the inventionfor the adapter according to the invention is capable of opticallydetecting the reference structure by means of the detecting unit and ofconsidering it in the control unit in order to control the beamdeflecting unit. If the laser processing device is designed for theLASIK procedure, the control unit can consider the desired shapeidentified by the information for control to obtain the breakthroughs tobe generated at the desired locations.

The invention will be explained in more detail below, by way of exampleand with reference to the Figures, wherein:

FIG. 1 shows a schematic view of a laser processing device for anophthalmic procedure;

FIG. 2 shows a schematic view of the cornea of a patient;

FIG. 3 shows a perspective view of a contact glass for the laserprocessing device of FIG. 1;

FIG. 4 shows a sectional view of the contact glass of FIG. 3;

FIG. 5 shows a top view of the contact glass of FIG. 3;

FIG. 6 shows a schematic view of the optical detection of a referencestructure of the contact glass;

FIG. 7 shows a perspective view of a contact glass for the laserprocessing device of FIG. 1;

FIG. 8 shows a sectional view of the contact glass of FIG. 7, and

FIG. 9 shows a top view of the contact glass of FIG. 7.

FIG. 1 shows a treatment device for an ophthalmic procedure, said devicebeing similar to those described in EP 1,159,986 A1 and U.S. Pat. No.5,549,632, respectively. The treatment device 1 of FIG. 1 serves toperform a correction of a visual defect in the eye 2 of a patientaccording to the known LASIK procedure. For this purpose, the treatmentdevice 1 comprises a laser 3 which emits pulsed laser radiation. Thepulse duration is e.g. in the femtosecond range, and the laser radiationis effective by means of non-linear effects in the cornea in theabove-described manner. The treatment beam 4 emitted by the laser 3along an optical axis A1 is incident on a beam splitter 5 which directsthe treatment beam 4 onto a scanning unit 6. The scanning unit 6comprises two scanning mirrors 7 and 8 which are rotatable aboutmutually orthogonal axes such that the scanning unit 6 two-dimensionallydeflects the treatment beam 4. Adjustable projection optics 9 focus thetreatment beam 4 onto or into the eye 2. For this purpose, theprojection optics 9 comprise two lenses 10 and 11.

Arranged following the lens 11 is a contact glass 2 which is securelyconnected to the lens 11 and, thus, to the beam path of the treatmentdevice 1 by a holder H. The contact glass 12, which is to be describedin more detail, contacts the cornea of the eye 2. The opticalcombination of treatment device 1 and contact glass 2 attached theretohas the effect that the treatment beam 4 is concentrated in a focus 13located in the cornea of the eye 2.

The scanning unit 6 is controlled via control lines (not identified indetail) of a control device 14, as are the laser 3 and the projectionoptics 9. In doing so, the control device 14 determines the position ofthe focus 13 both transversely to the optical axis A1 (through thescanning mirrors 7 and 8) as well as in the direction of the opticalaxis A1 (through the projection optics 9). The control device 14 furtherreads out a detector 15 which reads out radiation scattered back fromthe cornea, said radiation passing through the beam splitter 5 as backreflection radiation 16. Confocal imaging may be used for this purpose.The role of the detector 15 will be discussed later.

The contact glass 12 ensures that the cornea of the eye 2 is given adesired shape. Due to the cornea 17 contacting the contact glass 12, theeye 2 is in a predetermined position relative to the contact glass 12and, thus, to the treatment device 1 connected therewith.

This is schematically represented in FIG. 2, which shows a sectionthrough the cornea 17. In order to achieve exact positioning of thefocus 13 in the cornea 17, the curvature of the cornea 17 has to beconsidered. The cornea 17 has an actual shape 18 which differs frompatient to patient. The contact glass 12 now contacts the cornea 17 suchthat it deforms the cornea to a desired shape 19. The exact profile ofthe desired shape 19 depends on the curvature of the contact glasssurface facing the eye 2. This will become clearer later with referenceto FIG. 4. What is essential here is only that known geometrical andoptical conditions are given by the contact glass 12 for directing andfocussing the treatment beam 4 into the cornea 17. Since the cornea 17contacts the contact glass 12, which is in turn stationary relative tothe beam path of the treatment device 1 due to the holder H, precisethree-dimensional positioning of the focus 13 in the cornea 17 ispossible by controlling the scanning unit 6 as well as the adjustableprojection optics 9.

FIG. 3 shows a perspective view of the contact glass 12. As can be seen,the contact glass 12 comprises a glass body 20 which is transparent forthe treatment beam 4. The treatment beam 4 is coupled in at an upperside 21 of the frustoconical glass body 20, which upper side 21 isassigned to the lens 11.

The cornea 17 contacts a lower side 22 of the contact glass 12. As thesectional view of FIG. 4 shows, the lower side 22 is curved in thedesired shape 19 such that, when fully contacting the eye 2, it producesthe desired shape of the cornea 17.

A flange surface 23 is provided on the contact glass 12 near the upperside 21, on which flange surface the contact glass 12 is fixated in theholder H by clamps. The flange surface 23 represents a mounting meansbeing adapted to the holder H which realizes a locking mechanism.

By mounting the body via the flange surface 23, the main axis ofsymmetry A2 of the frustoconical glass body 20 is adjusted in secureconnection to the treatment device 21 and matching the optical axis A1.Inside the glass body 20 a reference structure 24 is formed, which isring-shaped in the exemplary embodiment. In the exemplary embodiment,the distance from the main optical axis A2 is selected to be as great aspossible, so that the reference structure 24 is located in the volume ofthe glass body 20 irradiated by the treatment beam 4 only if thetreatment beam 4 is deflected at near-maximum.

As FIGS. 4 and 3 show, the reference structure 24 in the volume of theglass body 20 is preferably located on or near the periphery of thefrustoconical glass body 20. The reference structure 24 consists of aplurality of reflector zones 25, which reflect the radiation emitted bythe laser 3.

The reflector zone 25 may also be applied to the upper side 21 or thelower side 22 of the contact glass 12, i. e. to the input or outputsurface of the adapter, in the form of a suitable laminar structure orof suitable reflecting or non-reflecting layers. It is also possible toprovide zones or layers with increased elastic scattering of light inorder to realize the reflector zones 25.

If the treatment beam 4 is incident on a reflector zone 25, radiationenergy is scattered back and is then picked up by the detector 15. Basedon the signal from the detector 15, the control device 14 can thusrecognize whether the treatment beam 4 is directed onto a reflector zone25.

As can be seen in FIG. 5, the reflector zones 25 are located near theperiphery of the lower side 22 along a ring shape. Together with thedeflection made possible by the scanning unit 6, the lower side 22defines the size and location of the processing zone. In case of faultypositioning of the processing zone on the cornea 17, there will be adeviation between a desired and an achieved refraction result, so that adesired correction of a visual defect may sometimes not be achieved. Thereflector zones 25 serve to compare the actual beam deflection with apredetermined desired value and to thereby minimize processing errors.

Deviations between the actual position of the beam and the predetermineddesired position on the cornea 17 may be caused, in principle, bymovements of the eye relative to the treatment device 1 or by faultypositioning of the eye 2 relative to the treatment device 1 or by faultypositioning of the scanning mirrors 7, 8 as well as of the projectionoptics 9. The contact glass 12 causes fixed positioning of the eye 2relative to the treatment device 1, because the cornea 17 is fixed viasuitable means, e.g. a suction ring (not shown in detail), at the eye 2.The reflector zones 25 now serve to be able to determine the position ofthe eye 2 relative to the treatment device 1.

The control device 14 controls the scanning unit 6 as well as theprojection optics 9 such that a laser beam is passed over the reflectorzones 25. For example, the control device 14 controls the laser 3 in amode of operation in which a beam 4 having only a strongly reducedradiation intensity is emitted. This may be effected, for example, byactivating or coupling in a suitable radiation attenuator. If the laser3 is a pulsed source of laser radiation, a much weaker backgroundradiation is possibly present also outside pulsed operation and can beused. Alternatively, it is possible to couple in an additional laser,for example via a further beam splitter being arranged preceding thescanning unit 3. Thus, said laser beam may either be the treatment beam4, possibly attenuated in a suitable manner, or a separate laser beamwhich is coupled into the beam path along the optical axis A1 before itreaches the scanning unit 6.

If the laser beam impinges on a reflector zone 25, the detector 15 givesa corresponding signal. If a reflector zone 25 is thus detected, thecontrol device 14 stores the thus given settings of the scanning unit 6as well as of the projection optics 9. After scanning at least threereflector zones 25, a complete determination of the actual position ofthe contact glass 12 and, thus, of the cornea 17 is achieved thereby.The control device 14 uses said actual position in order to place thefocus 13 at desired predetermined locations in the cornea 17 by means ofthe treatment beam 4 in subsequent treatment.

Due to the reference structure 24 along a ring at the periphery of theprocessing zone, unimpaired treatment is possible at the center of thecross-sectional surface which is circumscribed by the lower side 22 andthrough which the treatment laser beam 4 is coupled into the cornea 17.Given a sufficiently large numerical aperture of the treatmentradiation, the influence of the reflector zones 25, which are located inthe peripheral region of the processing zone, can be neglected duringtreatment.

The location of the reflector zones 25 at the periphery of the lowerside 22 allows the function of the scanning unit 6 as well as of theprojection optics 9 to be checked during current operation. In doing so,a relative deviation between the stored actual position of the reflectorzones 25 as well as when again checking assigned settings of thescanning unit 6 and of the projection optics 9 may then be taken intoaccount, in order to have deviations which occur during operationcorrected or, as the case may be, to block operation of the treatmentdevice 1 if there is too great a deviation.

FIG. 6 illustrates the process of detecting a reflector zone 25. Asignal S of the optical detector 15 is plotted therein as a curve 26.The focus 13 is guided from a point A to a point D along a path 27,which is usually three-dimensional, but is only representedtwo-dimensionally in FIG. 2, said point D covering the region in which areflector zone 25 is expected. During movement of the laser focus 13from point A, the detector 15 provides an idle value SO. Upon reachingpoint B, the signal changes and continuously increases, because backreflection occurs at the reflector zone 25. The respective coordinate xBin x-direction (the signal S is shown only one-dimensionally in FIG. 6with respect to the x-direction) characterizes the beginning of thereflector zone 25 in the x-direction.

Upon reaching the point C, the signal drops back to the idle value SO,and the coordinate xC indicates the end of the reflector zone in thex-direction. If the diameter of the focus 13 is small as compared to theextent of the reflector zone 25 and, thus, small as compared to thedistance BC, the clear separation of the leading edge at xB and thetrailing edge at xC represented in FIG. 6 is possible. In this case, theobtained information on the location of these coordinates can beconsidered in the control device 14 when determining the position of thereflector zone 25, if the reflector zone 25 has a known shape. On theother hand, if the diameter of the laser focus 13 is equal to or greaterthan the distance BC, the coordinates xB and xC are undistinguishableand the center of the reflector zone 25 appears in the signal S.

The position determination by optical scanning, which isone-dimensionally described in FIG. 2, is of course effected in threespace coordinates, so that the position of the reflector zone 25 isthree-dimensionally determined finally.

Detection of the reflector zone 25 in the treatment device of FIG. 1 maypreferably be confocally effected in order to obtain a maximumresolution along the optical axis A1 or A2, respectively (i. e. in thedepth direction).

FIGS. 7 to 9 show an adapter, which is designed as a contact glass 12,like that of FIGS. 3 to 5, but differs in the design of the referencestructure. Due to the otherwise identical features, reference is made tothe description of FIGS. 3 to 5, and the same reference numerals areused for the same features.

Inside the glass body 20 a code structure 24′ is now formed as thereference structure, which follows a ring shape in the exemplaryembodiment. In the exemplary embodiment, the distance from the mainoptical axis A2 is selected to be as great as possible, so that the codestructure 24′ is only located in the volume of the glass body 20irradiated by the treatment beam 4 if the treatment beam 4 is deflectedat near-maximum.

As FIGS. 4 and 3 show, the code structure 24′ in the volume of the glassbody 20 is preferably located on or near the periphery of thefrustoconical glass body 20. The code structure 24′ consists of aplurality of reflector zones 25, which reflect the radiation emitted bythe laser 3. If the treatment beam 4 is incident on a reflector zone 25,radiation energy is back-scattered, which is then picked up by thedetector 15.

The reflector zone 25 may also be applied to the upper side 21 or thelower side 22 of the contact glass 12, i. e. to the input or outputsurface of the adapter, in the form of a suitable laminar structure orof suitable reflecting or non-reflecting layers. It is also possible toprovide zones or layers with increased elastic scattering of light inorder to realize the reflector zones 25.

Based on the signal from the detector 15, the control unit 14 can thusrecognize that the treatment beam 4 is directed onto a reflector zone25. In total, the series of annularly arranged reflector zones 25 in thecode structure 24′ thus provides an encoded signal, which in theexemplary embodiment represents the curvature of the lower side 22 ofthe glass body 20 and, thus, the geometry of the desired shape 19 whichthe cornea 17 has with the contact glass 12 applied thereon. Thus, thecode structure 24′ realizes marking structures which identify ordescribe the contact glass 12.

In order to carry out this information extraction, which was alreadymentioned in principle, the control device 14, on the one hand, controlsthe laser 3 into an operating mode in which only a beam 4 with astrongly reduced radiation intensity is emitted. This may be effected,for example, by activating or coupling in a suitable radiationattenuator. If the laser 3 is a pulsed source of laser radiation, a muchweaker background radiation is possibly present also outside pulsedoperation and can be used.

Alternatively, it is possible to couple in an additional laser, forexample via a further beam splitter being arranged preceding thescanning unit 3. Thus, said laser beam may either be the treatment beam4, possibly attenuated in a suitable manner, or a separate laser beamwhich is coupled into the beam path along the optical axis A1 so as toprecede the scanning unit 6.

In order to read out the code structure 24′, the control device 14controls the projection optics 9 as well as the scanning unit 6 suchthat the focus of the laser radiation passes over the region in whichthe code structure 24′ is expected. The back reflections are recognizedin the signal of the detector 15, are assigned to the actual focusposition and are evaluated with regard to the encoded information withthe help of suitable means (for example, suitable processing electronicsand a memory element). Detection of the reflector zone 25 in thetreatment device of FIG. 1 may preferably be confocally effected inorder to obtain a maximum resolution along the optical axis A1 or A2,respectively (i. e. in the depth direction).

The information thus obtained about the adapter is then considered bythe control device 14 during the subsequent treatment of the cornea 17.For example, focus 13 is controlled by the scanning unit 6 and theprojection optics 9 such that the desired shape 19 of the currently usedcontact glass 12 is considered. Alternatively, the treatment device 1may also be blocked after having scanned an unsuitable contact glass, inorder to make treatment impossible. Additionally or alternatively,corresponding information on the currently used contact glass may beoutput by suitable means.

1-21. (canceled)
 22. An adapter for coupling a laser treatment devicewith an object to be treated, comprising: an adapter input side, theadapter being fixateable relative to the laser treatment device via alocking mechanism; the adapter being capable of transmitting a laserbeam to the object along an adapter beam path, the laser beam havingbeen supplied to the adapter input side and scanned over a region; areference structure, the reference structure being located in theadapter beam path and optically detectable by laser radiation scannedacross the region; and wherein the adapter can be brought into contactwith the object to position the object relative to the laser treatmentdevice.
 23. The adapter as claimed in claim 22, wherein opticaldetection of the reference structure allows the laser treatment deviceto check alignment of the adapter.
 24. The adapter as claimed in claim23, wherein the reference structure comprises at least one spatial zonewithin the adapter beam path, which differs from a remainder of theadapter beam path in at least one optical property.
 25. The adapter asclaimed in claim 22, further comprising an adapter output side, throughwhich laser radiation supplied to the adapter input side exits and whichcan be brought into contact with a deformable surface of the object andthereby imparts a desired shape to the deformable surface.
 26. Theadapter as claimed claim 22, wherein the reference structure reflectsthe actual spatial position of the adapter.
 27. The adapter as claimedin claim 25, wherein the reference structure comprises markingstructures which encode information about the adapter.
 28. The adapteras claimed in claim 27, wherein the reference structure comprisesspatial zones in the adapter beam path, which differ from a remainder ofthe adapter beam path in at least one optical property.
 29. The adapteras claimed in claim 28, wherein the optical property comprisesrefractive index.
 30. The adapter as claimed in claim 22, wherein theadapter beam path at least partially comprises a material which istransparent to laser radiation.
 31. The adapter as claimed in claim 25,further comprising a substantially cylindrical or substantiallyfrustoconical body, one end surface of which acts as the adapter outputside, the adapter output side conforming to the desired shape of thedeformable surface.
 32. The adapter as claimed in claim 25, furthercomprising a substantially cylindrical or substantially frustoconicalbody, one end surface of which acts as the adapter input side.
 33. Theadapter as claimed in claim 22, further comprising a flange forengagement to the locking mechanism.
 34. The adapter as claimed in claim22, further comprising a suction portion for attachment to the object.35. The adapter as claimed in claim 27, wherein the information encodedincludes the desired shape defined by the adapter output side.
 36. Theadapter as claimed in claim 35, wherein the information encoded includesrefractive properties of the adapter output side.
 37. The adapter asclaimed in claim 22, wherein the adapter comprises a contact glass foreye surgery.
 38. Laser treatment device comprising: an adapter, havingan adapter input side, the adapter being fixatable relative to the laserprocessing device via a locking mechanism, the adapter being capable ofbeing brought into contact with the object to position the objectrelative to the laser treatment device, wherein the adapter transmits alaser beam to the object along an adapter beam path, the laser beamhaving been supplied to the adapter input side by the laser treatmentdevice and scanned over a region; and a reference structure located inthe adapter beam path; a beam deflecting unit for scanning a laser beamover the region; a detecting unit for optical detection of the referencestructure by the laser beam; and a control unit, which receives outputfrom the detecting unit, controls the beam deflecting unit, determinesthe actual position of the adapter on the basis of the opticallydetected reference structure and considers the actual position whencontrolling the beam deflecting unit.
 39. The laser treatment device asclaimed in claim 38, wherein the control unit considers a differencebetween a desired position of the adapter and the actual position of theadapter when controlling the beam deflecting unit.
 40. The lasertreatment device as claimed in claim 39, wherein the control unitdetermines a difference between the desired position and the actualposition of the adapter and blocks treatment if the difference exceeds athreshold value.
 41. A laser treatment device for application of laserenergy to a deformable surface of an object, the laser treatment devicecomprising an adapter having an adapter input side, which can be fixatedvia a locking mechanism; the adapter being capable of transmitting alaser beam to the object along an adapter beam path, said laser beamhaving been supplied to the adapter input side and scanned over a regionand the adapter including a reference structure, the reference structurebeing located in the adapter beam path and optically detectable by laserradiation scanned across the region; the adapter including an adapteroutput side which can be brought into contact with the deformablesurface to position the object relative to the laser treatment deviceand which imparts a desired shape to the deformable surface when theadapter is in contact with the object, and wherein the referencestructure comprises marking structures which encode information aboutthe adapter; a beam deflecting unit for scanning a laser beam over theregion, a detecting unit for optical detection of the marking structuresby the laser beam, and a control unit which receives output from thedetecting unit, controls the beam deflecting unit, determines theinformation about the adapter and considers the information whencontrolling the beam deflecting unit.
 42. The laser treatment device asclaimed in claim 41, further comprising a pulsed treatment laser for anophthalmic procedure, wherein the object comprises the cornea, and thecontrol unit controls the beam deflecting unit and the treatment lasersuch that the laser beam generates optical breakthroughs atpredetermined locations in the cornea and, in doing so, considers thedesired shape of the surface of the cornea, and wherein the desiredshape is identified by said information.
 43. The laser treatment deviceas claimed in claim 41, further comprising a pulsed treatment laser foran ophthalmic procedure and by a device for attenuating laser beamenergy to allow optical detection of the reference structure.